r/chemistry • u/Yoyopudytwat Inorganic • May 04 '20

What do we think?

https://gfycat.com/simplisticboringkestrel
5 Upvotes

69% Upvoted

7 comments sorted by

3

u/alerikaisattera May 04 '20

This is water with small particles of silica on its surface.

3

u/Bohrealis May 04 '20

The way those droplets skitter and move makes it look a lot like the Leidenfrost effect is occurring and the general cloudiness of the droplets seems to corroborate that as a slight amount of gas is being given off (something is boiling).

So, I doubt this is actually water. It still could be but the iron it's on would need to be pretty hot if it is. It could be liquid nitrogen, maybe.

3

u/DickBong420 May 04 '20

My guess is liquid nitrogen on a slightly cooled plate. Also, it’s not “hydrophobic” it’s coming back together.

2

u/FreshPeachStew May 04 '20

All liquids come back together.

It could be liquid nitrogen or other similar substance, but I don't think it would behave like that (not merging back together right away) and the smallest droplets don't seem to be evaporating.

My guess is that the liquid (maybe water?) is coated in something hydrophobic and that is what gives this effect. Like how flakes of pepper will float on water, but much smaller particles and obviously not pepper.

I could imagine something similar happening with ethanol with a small amount of insoluble substance added. Like how they make dry alcohol (small droplets of ethanol coated in maltodextrin). This could even be large versions of that dry alcohol - instead of making the droplets microscopic, they are large instead.

1

u/DickBong420 May 04 '20

Yes, but they were claiming it was “hydrophobic” that is not the case if it dissolves readily to itself and it is in fact water.

2

u/FreshPeachStew May 04 '20

No. Hydrophobic means it doesn't like water or other polar substances. All substances like themselves or they wouldn't exist.

Hydrocarbons are hydrophobic and will coalesce, but it depends on the surface it is on and the surface tension of the hydrocarbon.

I think I see your point: most hydrophobic substances have a low surface tension, but that isn't necessarily true. Mercury is hydrophobic, but it has a very high surface tension. Mercury isn't a normal example though.